The companion having a gun does restrain one (7)
I believe the answer is:
chasten
'restrain one' is the definition.
'chasten' can be an answer for 'restrain' (thesaurus). I am not certain of the 'one' bit.
'the companion having a gun' is the wordplay.
'the companion' becomes 'cha' (Companion of Honour).
'having' says to put letters next to each other.
'a gun' becomes 'sten' (British sub-machine gun).
'cha'+'sten'='CHASTEN'
'does' is the link.
Can you help me to learn more?
(Other definitions for chasten that I've seen before include "Have a restraining effect on (someone)" , "Suppress" , "Subdue the pride of, discipline" , "Subdue, correct by punishing" , "Humble" .)